


Pretty in Lace

by Nanenna



Category: Undertale (Video Game)
Genre: Aftercare, Enthusiastic Consent, Established Relationship, M/M, Oral Sex, Orgasm Delay, Overstimulation, Sacrum Lacing, Sensitive bones, Unrealistic Sex, sansby - Freeform
Language: English
Status: Completed
Published: 2019-11-03
Updated: 2019-11-03
Packaged: 2021-01-22 09:53:35
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,327
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21300005
Author URL: https://archiveofourown.org/users/Nanenna/pseuds/Nanenna
Summary: Sans spends the night over at Grillby's, for two such mellow monsters they sure don't have a mellow evening in together.
Relationships: Grillby/Sans (Undertale)
Comments: 13
Kudos: 173





	Pretty in Lace

**Author's Note:**

  * For [skerb](https://archiveofourown.org/users/skerb/gifts).

> Happy birthday Skerb!  
Also a big thanks to Enneadodeca for the whole fire lacing thing. Damn that's such a good idea!

Sans grins to himself as he watches Grillby strip off his work clothes, he has quite the view from his vantage point of lounging against the pillows on Grillby’s bed. Despite how neatly Grillby usually dressed he wasn’t very fussy about the way he undressed, fingers quickly and nimbly working to undo his tie and buttons only to drop the clothes somewhere near the laundry basket. Once down to just the last layer, Grillby gets on the bed and crawls over to Sans.

“what? gonna keep the skivvies on?”

“… Not fair you’re still dressed,” Grillby replies, tugging at Sans’s hoodie.

“thought you might have some fun unwrapping me.”

Grillby grumbles, but the sounds die in his throat when Sans wraps his arms around Grillby’s neck and pulls him into a deep kiss. Their magics spark and intertwine wherever they brush against each other, leaving them both tingling and their mana rushing. Without breaking the kiss, Sans moves a hand up to play with the flames that are Grillby’s head.

Grillby moves his hands under Sans’s hoodie and starts pushing it away, the sleeves straining against his arm pits. Sans grumbles as he breaks the kiss, but he put too much work into making this custom hoodie to let Grillby burn it off. The rest of his clothes… eh, he’s not too attached. If Grillby wants to set his pants on fire he’ll let him. Sans sits up and, with a little help, soon has the hoodie off and tossed to the far corner of the room, followed quickly by the rest of his clothes. Then they’re kissing again, Sans is pulled fully into Grillby’s lap before hands start wandering over each others’ bodies.

Grillby’s fingers trace the dips and bumps of Sans’s spine as he works his way slowly down until they reach his sacrum, one finger tracing a hole before curiously wedging in. Sans jolts and gasps.

“… You alright?”

“yeah just uh… just wasn’t expecting that. not a lot usually goes in there, kinda sensitive, ya know?”

“… Hm… not really.” Grillby idly runs his fingers over the holes.

“guess it’s a skeleton thing.”

“… You said not a lot, does that mean things do go in there?” Now only one finger is on his sacrum, it wedges itself back into one of the foramina.

“s-sometimes,” Sans agrees shakily.

The finger changes from plugging to rimming. “… Anything in particular?”

“plugs or ribbons, i got a ha…” Sans’s fingers dig into the undershirt he’s clinging to, “a uh… a collection.”

“… Interesting.” Grillby pulls back, both to draw his hand away from distracting Sans and to get a better look at his face as he asks his next question, “… Ever had someone else’s magic in there?”

“what? like a tentacle?”

“… Something like that.” Grillby sets Sans a little away from him, sitting back so he can hold up his hands between them. As Sans watches he brings his index fingers together until they touch, then draws them slowly apart, a string of what appears to be orange magma connecting them. “… I was thinking something more like this.”

Sans swallows, his mouth suddenly overfull. “that’s new.”

“… Are you interested?”

“hell yeah.”

What follows is a flurry of activity as the two fumble their way into position, distracting each other with kisses, Sans’s explanations interrupted by giggling or a wild grope. Sans ends up enthroned at the head of Grillby’s bed, his few pillows piled behind him, his coccyx in Grillby’s lap, legs spread wide on either side of his waist.

“… It won’t hurt you?”

“you know how it is, if you don’t intend to hurt me it won’t.”

Grillby nods, then slowly, carefully inserts his thread of magic (now thick as yarn, isn’t that a delicious thought?) through the first hole.

Sans tenses up, hands reaching for the bars of Grillby’s headboard behind him on pure instinct. He clings to it tightly, trying to force himself to start breathing again.

“… You okay?”

“y-yeah,” Sans breathes. He forces a deep, shuddering breath before continuing, “just a lot to take in all at once.”

“… Not too much?”

“no, just uh… just different. It’s more intense than a regular ribbon.” Sans’s lids fall to half mast and he nods to Grillby, “keep going.”

“… As you wish.” Grillby pulls the thread through, Sans gasps and tenses at the sensation again, toes curling and heels digging into the bed.

It’s so different from a ribbon, then the sensation is purely physical, here it’s Grillby’s magic interacting with his own directly, interfering with the ley lines and mana flow through his sacrum and yet the only physical sensation is the soft heat radiating off the piece of magic and the occasional ghost of something rubbing in a far too sensitive area. More than that, though, is the sheer _intent_ of their magics touching so intimately without fabric, bone, or living dust to muffle it. _Amusement_ and _pleasure_ seem to almost skip right over his sacrum to shoot up his spine and directly into his soul.

“… You seem to be enjoying yourself.”

Of course _intent_ is a two way street. Sans grins hazily at Grillby, desperately trying to gather his scattered thoughts back up (and they’d just barely started, Sans was going to be an absolute **wreck** later). “not sure how to explain it to a non-skeleton. but it feels good. real good.”

Grillby smirks like he already knew.

Sans is prepared for the next one. Well, better prepared, anyway. Grillby first carefully draws the thread through, then starts the next insertion. Sans tenses again, still clinging to the headboard so hard he’s pretty sure his fingers are going to light up soon, if they aren’t already. Once the thread is through Grillby stops to let Sans adjust. Sans lets his skull flop back against the headboard as he wills himself to relax.

They continue like this, Grillby slowly, gently, carefully inserting his magic into Sans’s foramina, giving Sans time to adjust, then drawing the thread through until it’s just snug before starting on the next one. Sans is pretty sure that as living magic he doesn’t need to pull it tight, but it also feels pretty damn good so he’s not going to ask Grillby to stop. Grillby’s face stays an unreadable mass of flickering flames. Sans, on the other hand, has dropped his usual grinning mask altogether, a bit of drool leaking from his slack jaw or his teeth clenched tight. His grip tightens and loosens from the headboard but never quite lets go, his feet digging into the mattress or occasionally kicking the air. Once, when Grillby is near the end and letting Sans adjust between insertions, Sans looks down to see the undershirt Grillby is still wearing painted in hues of sharp blue.

Sans isn’t quite sure why he hasn’t cum yet, he really should have by now. The way his sacrum is being warmed so deliciously combined with nearly overpowering _intent_ being fed into him by Grillby and just how full he’s being stuffed has his soul twisted tighter than a wind up toy. It could be the way Grillby is letting him relax between insertions, but Sans has been so close to the edge for so long that he’s pretty sure it’s less that and more the way Grillby’s magic is interrupting his mana flow. It’s probably going to hit him all at once when Grillby unlaces him. It’ll certainly be an interesting experience to have his hypothesis put to the test.

Grillby inserts the thread through the last foramen, Sans gasps and grips the headboard all the harder, head thrown back into the pillows, spine arched and tense as a drawn bow, his legs hitch around Grillby’s waist before squeezing him tight. He’s so close, he’s so damn close, and yet he doesn’t tip over the edge. He’s stuffed far too full, his magic lying thick and heavy in his pelvis but unable to form, the sweat sliding over his bones doing nothing to cool the heat and _pleasure_ radiating from his sacrum through the rest of his bones.

Grillby ties the thread into a little bow, that done he lets Sans’s pelvis rest fully in his lap as he leans back on his arms to better admire the fruits of his labor. Sans can feel something hard poking his coccyx.

“… Your magic is such a pretty color,” Grillby comments absently as one hand drags through the thick haze of magic swirling in Sans’s pelvis.

“lemme suck you off,” Sans replies almost desperately.

“… what?”

Sans’s legs don’t feel quite all there, he flops and stumbles without coordination as he tries to get turned over and around. “lemme suck you off, i want this to be fun for you too.”

Grillby helps steady Sans as he fumbles his way around, every movement sending little shudders from his sacrum up his spine. When Sans ends up face planting into Grillby’s lap he swears he feels the thread _throb_. There’s the sound of fire snapping and crackling, what he recognizes as the fire elemental equivalent of chuckling, and then a pair of warm hands are helping Sans get adjusted into a more comfortable position. Sans swears the thread is rubbing over his bones far more than a regular ribbon ever would, he would have his suspicions about that if he could think straight.

That’s a lie, nothing about Sans is ever straight, especially not his thinking.

It takes a bit of pawing and a few tries, but Sans manages to get Grillby’s underwear pulled away and his dick free. He takes a moment to admire it, the warm, buttery color it glows, just how girthy Grillby is, the magma-like precum leaking from the head. Sans thumbs the opening, giving the whole shaft one long, slow pump to help spread the pre before taking the head into his mouth. It’s Grillby’s turn to moan and throw his head back, a warm hand pressed into the back of Sans’s skull.

Sans tries to get into a rhythm, he really does, but the way the thread rubs through his sensitive foramina and the way it’s shooting Grillby’s _eagerness_,_ anticipation_, and _**pleasure**_ directly into Sans’s soul is far too distracting. Every groan and gasp he sloppily sucks from Grillby is mirrored by the thread throbbing. Or maybe it’s Sans’s own mana throbbing, he can’t tell anymore. All Sans knows at this point is Grillby, Grillby, Grillby, his every sense filled with him. Grillby’s smoky scent, his warm hands on his body, his warm body under his own hands, his taste in his mouth, his soft moans in his ear canals, his magic warming his pelvis. Sans’s whole world has narrowed in to be full of nothing but Grillby.

Too bad Sans is so off his game, it’s probably the crappiest blow job he’s given since college, but it seems to get the job done. Grillby gasps, “… Sans,” as warning. Sans hums in reply, the vibration enough to tip Grillby over the edge. Sans is so off his game that he doesn’t even manage to swallow most of it down but eh, it’s not like this is the first time they’ve gotten jizz all over Grillby’s bed.  
  


Grillby looks down to see Sans splayed out in his lap, trying to his damnedest not to even twitch, eyes half lidded but pips over bright, grin satisfied but strained at the corners. He moves the hand gripping Sans’s skull down to the side of his face, a thumb tracing over his brilliantly flushed cheek bone. “… How about we finish you off now?”

“don’t uh… don’t think we can while i’m laced,” Sans admits haltingly. “would’ve a few times over by now if i could.”

“… Oh.” Grillby feels foolish not to have noticed sooner, that certainly explained the way Sans had been squirming delightfully while he’d still been lacing him. He wastes no more time, quickly scooping Sans up to flip him front to back, an arm supporting his ribs, his scapulae resting against Grillby’s abdomen, his pelvis resting on the bed between Grillby’s thighs. Grillby bends over his small lover, his free hand reaching down to touch the thread of magic tied up in a bow. The moment he touches it he dismisses it.

Sans screams and arches, heels dug into the bed, the magic swirling in his pelvis sparks and snaps with repressed magic released all at once, sockets open wide to show his pips had morphed into pink hearts. Then the sockets go empty and Sans goes limp. Grillby grimaces, perhaps he should have taken that a bit slower.

He arranges Sans to rest in his own lap, careful to have all his limbs resting easily, a hand pressed over his eye sockets to close the lids. He’s just finished settling Sans and bending over him for a better look at his face when Sans’s lids flutter open, hazy, dim eye pips flick around a moment before focusing on Grillby’s face. Grillby smiles down at him, glad Sans has woken up.

“… That was perhaps a bit too much at once.”

“yeah,” Sans responds fuzzily, “a bit.”

“… How do you feel?”

“mmmm… floaty.” Sans wiggles a little, likely settling himself in comfortably. Grillby starts petting his skull, hoping the motion is as soothing for Sans as it is for him. A quiet, rumbling buzz starts up, one of Sans’s rare purrs. Grillby’s smile spreads wider.

“… Alright, how about we just stay like this for a while?”

“yeah, sounds good.” Sans seems to drift off then, not quite all the way asleep but content to just drift in the moment.

Grillby relaxes himself, continuing to stroke Sans’s skull. He’s careful to keep his intent _calm_ and _soothing_ even as his eyes rake over Sans’s bare bones. He’s considering all the lovely empty spaces a skeleton is made of, each one begging to be filled with fire in one way or another. Perhaps Sans would be willing to try this again sometime.


End file.
